The present invention relates to a chronographic watch comprising a timepiece mechanism and a stop-watch mechanism, which respectively indicate absolute time, and effect the measurement of more or less short intervals of time. Two different kinds of such watches exist: chronographic watches with digital display and those with analogue display. Electronic digital watches have the advantage that they comprise, in addition to the timepiece mechanism and counters which merely count seconds, minutes and hours, recall systems that enable simultaneous events to be timed. Such watches can readily be provided with a wide variety of functions which can be achieved by electronic counting circuits but which would be difficult to achieve by mechanical means.
Analogue chronographic watches have the advantages of all analogue timepieces, that is to say the rapidity with which elapsed time and time to go can be determined; these advantages are appreciated in certain professions and among those responsible for deciding the results of sporting events. They also have the elegance and aesthetic appearance of watches provided with dial and hands.
It would obviously be possible to motorize a mechanical chronographic watch with the aid of a conventional electric motor. This solution, which is not very elegant, would necessitate the use of a motor with a shaft which advances at the rate of ten steps per second, which would involve a high consumption of energy, even when the chronographic mechanism is stopped. Moreover, certain advantages of exclusively electronic devices could not be retained. It would also be possible to envisage the super-imposition of a watch and a counter one upon the other, each of them having its own independent driving means. This complicated and not very elegant construction would not enable this watch to be produced as a commercial product.